Women who gain or lose loads of weight between pregnancies might be putting not only themselves, but also their babies at risk, warn experts.

The finding is based on research by Jennifer Walsh, a specialist registrar in obstetrics and gynaecology at Coombe Women's Hospital, Dublin, UK, and Deirdre Murphy, professor of obstetrics at Trinity College, University of Dublin.

The researchers point out that their study is particularly relevant to present times as women are being bombarded with mixed messages about diet, weight and body image.

These messages are now also extending into pregnancy, they state.

As a part of their research, the two authors analysed two Swedish studies involving 207,534 women.

The first study showed that there was a strong link between major complications for the woman and baby in the months preceding, during and just after childbirth and weight gain between pregnancies.

The second study found that losing weight was equally not good, as women whose weight fell significantly between pregnancies had a higher risk of giving birth prematurely.

With at least half of all pregnancies unplanned, the authors state that women need to be made aware of the implications of 'yo-yo' weight on them and their babies.

'Pregnancy is one of the most nutritionally demanding periods of a woman's life, with an adequate supply of nutrients essential to support foetal wellbeing and growth,' the BBC quoted the authors as saying.

'With at least half of all pregnancies unplanned, women need to be aware of the implications of their weight for pregnancy, birth, and the health of their babies.

'Women are at an increased risk of different but equally serious adverse pregnancy outcomes if they gain or lose an excessive amount of weight between pregnancies," they added.

They advise women with a normal weight to avoid piling on the pounds between pregnancies, and advise overweight women to shed excess pounds before pregnancy.